Book forming and pressing apparatus commonly use creasing irons, called nippers, to crease a book in its hinge area. In addition to pressure, heat is also used to assist in forming the book covering material and heating the adhesive within the book. Conventional nippers are heated by the use of an individual electrical resistance cartridge heater mounted within each creasing iron assembly to indirectly heat its nipper by conduction.
The creasing iron assemblies are normally mounted on a carriage transported by a continuously moving endless conveyor chain with the creasing iron assemblies in predetermined uniformly spaced relation to one another. An adjacent carriage, movable in an opposite angular direction, is provided with corresponding creasing iron assemblies, and matching creasing iron assemblies are transported by their respective carriages into opposed spaced confronting relation to one another in timed relation to the passage of a book along a feed path between the carriages. Each corresponding pair of creasing iron assemblies are thus driven in synchronism with one another and engage one of an oncoming stream of books to form a desired crease on both sides of each book in its hinge area.
Carbon copper contamination is prevelant in such conventional machines and is discharged from electrical brushes supported in trollies which ride along charged feed rails to provide the required electrical energy for heating the individual cartridge heater within each creasing iron assembly. Moreover, conventional machines normally have exposed bearings which provide for spray mist lubrication. The undesired contamination has been found to reduce the lubricant life and to cause bearing assemblies to wear more rapidly in addition to promoting undesired electrical arcing. Also, failure of a cartridge in any one creasing iron assembly will result in the book production with poor quality creases. Under normally high production speeds, a number of books of poor quality are normally produced before such failure is detected, and then the machine must be shut down and the required repair results in further loss of production time.